Sunday Night Doppelgangers

“Somewhere in the world, we all have at least one person
who looks exactly like us.”

Melissa Doyle, Sunday Night, 18 August 2019

Last night the television program Sunday Night aired an interesting segment discussing the notion that each of us isn’t the only person on the planet who looks exactly like us – something she refers to as a doppelganger.  Doppelgangers are non-biologically related ‘twins’ of ourselves, though usually a doppelganger has a negative connotation – that the doppelganger is an evil or ghostly twin. Not in this case though.

Sunday Night’s segment on dopplegangers shows how confusing similar looking people in photos can be.  There are many fascinating pairs of doppelganger in this broadcast (which you can see using the 7Plus link in the reference below).  It is captivating to see how alike people can look.  It also seemed an ideal opportunity to demonstrate simple ways to distinguish between individuals in photos and work out if they are or are not the same person.  So what can you look for?

The ‘ears’ have it


‘Doppelgangers’ , Channel 7 ‘Sunday Night’ [1]

In this example, former President Barak Obama (right) seems to have a twin.  But in the briefest of glances an aware photo viewer can see that they are not the same person just by looking at the ears.  The man on the left has strongly attached earlobes, while Obama has completely free (unattached) earlobes.   Barring any accident or damage to the ear, ear shape is purely genetically dictated, and, since ears are complex and variable, ear shape is often different from person to person, and one of the easiest ways to rule out people in photos as matching  – it’s not the same person if their ears don’t match!

Face size matters

But what if the ears aren’t visible or don’t help you identify or rule out the identity of the person in the photo?  Look a bit more closely at the size of the face.  In these photos of John (left) and Neal (right), it is easy to see that John’s face is almost 10% longer than Neal’s face:


Doppelgangers John and Neal [1]

Shape and Colour

But what if they seem to have similar sized heads, or you can’t see their ears as in the photo as in the photos of Niamh and Karen below? There are so many ways in which their faces look similar, especially with matching makeup and hair. How could you tell them apart?


Doppelgangers Niamh and Karen [1]

Well, have a look at their eyes.  You’ll have to zoom in.


Doppelgangers Niamh and Karen – Details of eyes [1]

Look at the differences: the eye colours are a bit different as Karen (right) has greener eyes than Niamh (left), and Niamh’s eyes are shaped differently (more almond shaped and sharper in the inner corners). This is easy to see if you look carefully, even though their eyebrows and lashes have been made up to look identical. The trick is to focus on and compare individual parts and aspects of a person’s face, rather than to view it as a whole.

Hopefully these simple tips will help you next time you’re trying to decide if that woman in a family photo is your Aunt Judy or your Aunt Evelyn!

Doppelgangers, Sunday Night (18 August 2019) Accessed 19/8/19. Images used under ‘fair use’ provisions of copyright law.

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Born or Built? My excellent adventure with Questacon


Read in Spanishsmall_20190328_110956

This morning I attended the launch of Questacon’s Born or Built? exhibit.  I was invited because I feature in it! Yes, that’s right, along with a few others of my colleagues I am part of the exhibit, expressing my views as a computer scientist on aspects of robotics, from our relationship to them, through to serious ethical questions such as who is responsible for them and their actions.  Here I am!


This exhibit is the culmination of more than a year of extraordinary work by the Questacon team (Doug, Matt, Alex, Jason are the delightful people who engaged with us on the exhibit).  There are so many engaging activities in the exhibit, and of course robots.

small_20190328_10424520190328_104419Our Human Centred Computing team, led by Professor Tom Gedeon, met with the Questacon crew several times to offer input into some of their already admirably managed strategic directions, and one of our group, Sharifa Alghowinem, was a key contributor to the “Is this a face?” activity.

Last spring (that’s October here for my USA readers) Alex asked me if I would be willing to be filmed for this exhibit.

I gulped, applied makeup for the first time in 10 years, and went.  I’m so glad I did! It is extraordinary seeing yourself weighing in on important matters alongside notable peers, knowing that perhaps 500,000 people or more might listen to my views in the coming year.

The launch was a great affair, with Questacon Director Graham Durant speaking and the Australian Chief Scientist, Dr Alan Finkel formally opening the exhibit. Our College Dean, Professor Elanor Huntington, spoke at the event as well. An enormous group of children excitedly trying out all the activities and a quite active robot brought life (both human and robotic) to the exhibit.

When you get a chance, be sure to pay a visit to this exhibit.  It is super fun, mind-expanding, and profound.


p.s. I couldn’t resist adding this snap in as well.  I have never had my name in lights before!



All images by Sabrina Caldwell – taken with a Samsung cellphone.  Images cropped and resized for web use.
No other changes made.
Questacon exhibit home page

To see Dr Alan Finkel Chief Scientist tweets on this event:




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Ringing the New Year Resolutions: Photos ‘just because’

Photos ‘just because’

Sometimes I find myself not posting anything on this blog because I want to ensure I keep to my mission of “a public forum to explore the art, technology and social implications of photographs, photoart, and everything in between.” [1]  In doing so I cheat myself of the fun of sharing my photos ‘just because.’ So for 2019 I’ve decided to sprinkle in more photographs.

Dolichopodidae fly

Here’s the first example (only 86 hours into the New Year too; I’ve also decided to procrastinate less).  It is a tiny green metallic fly that obligingly scurried up and down the rail of our back deck for the time it took me to take over 4 dozen photos with my new Canon 58-100mm  macro lens.  Only about 7 of the 50 were in the ‘good’ range, and these are the 4 best of them. Not bad for my first try at macro photography!

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I tried to identify this fly, and tentatively identified it as being a ‘long-legged fly’ in the family of Dolichopodidae.  As tiny as he is (perhaps 5-6mm), he is a predator fly, who eats other insects even tinier than himself [2].

Certainly they have the required speed; here’s a photo of him taking off while I was clicking the shutter button!




All photos cropped for web-use only – no other changes.

[1]  About page

[2] Joseph M. Cicero, Matthew M. Adair, Robert C. Adair, Wayne B. Hunter, Pasco B. Avery, et. al.  (2017) Predatory Behavior of Long-Legged Flies (Diptera: Dolichopodidae) and Their Potential Negative Effects on the Parasitoid Biological Control Agent of the Asian Citrus Psyllid (Hemiptera: Liviidae)   Florida Entomologist, 100(2) : 485-487  Florida Entomological Society URL:  Accessed 4 January 2019.





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Daniel Boorstin (1914-2004)

“The greatest enemy of knowledge is not ignorance,
it is the illusion of knowledge.”

Daniel Boorstin [1,2]


[1]  Boorstin quote referenced by Godfrey Hodgson in “Prolific American social historian who charted the corrupting influence of advertising and spin on political life”
[2] Boorstin was the 12th Librarian of Congress for 12 years from 1975-1987.  Nice symmetry!

Daniel Boorstin said it in 1962…

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Posted by on December 18, 2018 in Quotes


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The eclipsed moon 28 July 2018


Total lunar eclipse

This weekend we here in Australia were treated to a total eclipse of the Moon, provided one could rouse oneself from sleep at 4:30am on a chilly winter morning  to view it.

The night was bright with the glow cast by the full Moon when I walked outside; the sky was wonderfully clear.   The shadow of the Earth was already taking the tiniest nibble from the top right corner of the Moon’s light.  The blinding glare of the full moon slowly gave way to the penumbral shadow, with details of the lunar landscape becoming visible, first in gray, then russet.

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Once the full face of the Moon was shadowed, and the Moon moved deep into the Earth’s umbral shadow, the colours of the Moon transformed into a sanguine sphere.


As the red-shadowed Moon sank in the West, it skimmed the tops of the Norfolk Island Pines, which added another layer of shadow (albeit an Earthly one), creating unexpected lacey patterns.

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Trailing the eclipsed Moon down the sky was Mars.  Close to the Earth at apogee, [1] Mars seemed larger than usual, while the Moon, whose orbit is at perigee, seemed smaller then usual.  The juxtaposition of these two extremes of orbital distance created an unusual proportionality.


As the Sun lightened the sky, the Moon and all its colourful glory began to fade into the horizon and the dawn. I stood there, with the Sun at my back and the Blood Moon before me, and felt connected to the Sun and the Moon and the Earth and Mars all at the same time: the Sun rounding the Earth was bringing an end to the enormous shadow cast by the Earth beneath my feet upon the Moon at the horizon with its companion Mars gliding silently behind.



All photos cropped and resized for web use.  No other changes made.

[1] Mars is 35.8 million miles (57.6 million kilometers) per NASA  Accessed 29 July 2018

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Posted by on July 29, 2018 in Astronomy


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Shedding light on a bike accident photo


Every March I have the pleasure of speaking to students studying web development and design at ANU about images and image credibility.  One of these students sent me this photograph, a tragi-comic image that makes one wince and laugh at the same time.

As an image credibilitist, I was intrigued.  Was it real?  It’s not hard to imagine a photographer with the good fortune to be photographing someone doing a bike trick that went horribly wrong right in front of the camera. 

I examined it closely.  Everything seemed to look correct from the shadows on the ground to lines that resembled impact waves on the man’s face.  Further, it put me in mind of a similar accident that happened to one of my brothers – the loss of a front wheel off the bike fork leading to a complete wipe-out.

Despite this, I was yet to be convinced.  Was the scene a bit too ‘lined up’?  Was the escaping wheel too conveniently positioned square to the camera?

As a stared at the photo and the quite distinctive shadows on the concrete, I thought about the famous Australian photographer Frank Hurley and a particular Antarctic photograph I  wrote about in some previous research.  


‘Ocean Camp, Weddell Sea’  Frank Hurley, 1915 [1]

Hurley took this extraordinary photo during the Shackleton Imperial Trans-Antarctic Expedition  (1914-1917), recording the harsh conditions of the Weddell Sea ice shelf.  At the same time it also wonderfully records the beautiful oddity of penguins and the indomitability of life in the face of severe adversity.

However, it is a composite image. It is easy to see if we look to the shadows.  The dark sled dogs and sled in the mid-ground cast long shadow leading right and down, indicating that light source (the sun) was behind and to the left.  Simultaneously, the foreground penguins cast no shadow, in fact they seemingly lit from the front.  Since it would defy the laws of physics for both of these things to be true at the same moment, the image has to be composited. [2]

Remembering that, and having recently read an article in which a leader in my field, Professor Hany Farid at Dartmouth College, commented about the importance of shadows as a key to ascertaining the veracity of an image [3], I looked more closely at the shadows in the bike accident photo.  Well, they looked as they should.  So that wouldn’t tell me anything.  Hmmm, or would it? 

I imported the image into Powerpoint and superimposed lines connecting features of the main objects in the image to their shadow points on the pavement. In short order, I had my answer.  I won’t keep you in suspense any longer. My assessment of the Falling Bike Guy is that it was not only composited, but staged as well.  The photograph is not a photograph, it is photoART.


The lines in this image show the directionality of the light source.  Clearly the escaping wheel was lit by sunlight coming from the top right, and the falling guy is lit by sunlight coming from the top left.  This indicates that the sun was in a different position at the time of each photograph.  The middle element is more confusing.  At the moment, I have tentatively suggested that the light source for the upended Schwinn comes from two slightly different positions of the sun (perhaps from being held up from first one side then the other?), but I may explore this further.  At the very least, the average light source position is different from both the escaping wheel and the falling guy.

Logically, if the three main elements of the image were taken at different times, then the falling man is not involved in an accident, but instead is staging himself to appear as though he was. With either the assistance of a friend, or with a camera on a tripod with a remote trigger, timed shutter, or bracket photography (or a combination thereof), our man collected several photographs, then composited them in Photoshop or a similar photo editor.

In fact, if one visits ‘Gratisography’ [4], the site from which this image was sourced by my student, it is a simple matter to discover that the man in this image is in fact Ryan Mcguire himself, the founder of Gratisography.

So next time you find yourself wondering whether a photograph is real, take a closer look.  You may find your answer lurking in the shadows.


[1] Hurley, Frank (2015) Ocean Camp, Weddell Sea. In the collection of the National Library of Australia Ref: NLA.pic.an24039566-v
[2] Hurley later admitted to the compositing, and explained that  he couldn’t portray the entire feel of the experience without bringing different things together into one image. I believe I learned this in a book by Helen Ennis of ANU on Hurley’s Antarctic photography.   (quote/reference to be added soon)
[3] Eric Kee, James O’Brien, and Hany Farid. Exposing Photo Manipulation with Inconsistent Shadows. ACM Transactions on Graphics, 32(4):28:1–12, 2013.
[4] Gratisography, Ryan Mcguire, .




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Knowledge credibility in popular culture: The X-Files


If you could peruse the titles in my entertainment collection you would notice an inordinate over-representation of science fiction, among which is an abundance of The X-Files DVDs.  From the early days of Dana Scully [1] struggling unsuccessfully to rein in Fox Mulder’s [2] paranormal proclivities, to the persistent conspiratorial high jinks that saw the two investigators locked in story-arc combat with shadowy government figures, to today when the selfsame couple return in a later incarnation and convincingly reposition themselves in the X-Files saddle, I’ve loved it all.


Fox Mulder and Dana Scully, The X-Files, 20th Century Fox

Meanwhile, back in the real world, I’ve spent years soberly researching the credibility of images (widened recently to knowledge credibility generally) and the computing and social solutions we need to re-instill trustworthiness in our knowledge infrastructure. This subject has only recently become popular in the public zeitgeist.

So you can imagine the dizzying moment yesterday when my academic world collided with my X-Files fan world while watching the 4th episode of the current season to hear the following exchange between Mulder and the mysterious Dr They:

Mulder: As long as the truth gets out…

Dr They: Oh, they don’t really care whether the truth gets out, because the public no longer knows what’s meant by the truth.

MulderWhat do you mean?

Dr They: I mean no-one can tell the difference anymore between what’s real and what’s fake.

Mulder: There’s still an objective truth, an objective reality.

Dr They: So what? I mean you take this Mandela effect [3]. Well, in the old days I would never have come out and admitted to you that yes I can change people’s collective memories. And that would have meant that I can control the past. And if that’s true, well as Orson Wells once said, “He who controls the past controls the future.”

Mulder: It was George Orwell that said that.

Dr They: For now, maybe.  Anyway, the point is that I can say all of this right out here in the open because it doesn’t matter who hears, they won’t know whether to believe it or not.

Mulder: To be honest, I’m not believing any of this.

Dr They: Well, believe what you want to believe, that’s what everyone does nowadays anyway.  … You know our current president once said something really profound.  He said “nobody knows for sure.”

Mulder: What was he referring to?

Dr They: What does it matter?


So it has finally happened – the concerns I’ve been espousing for years to often deaf ears are finding expression in mainstream popular culture.  And not just any popular culture, but my much loved X-Files. [4]  Have to make some slight mental adjustments, but hey, super news!.  Hmmm — and just a bit spooky.


[1] Brilliantly acted by Gillian Anderson.
[2] Portrayed by the timeless David Duchovny, who also played the lead role in one of my favourite ‘feel great’ movies of all time: Return To Me.
[3] Changes to collective human memory.
[4] Chris Carter (creator). The X-Files Season 11 Episode 4 “The Lost Art of Forehead Sweat”.  (2018)  20th Century Fox. Aired in Australia 25 January 8:30 pm Foxtel.  Transcript and screen capture image used in line with fair use provisions of copyright law. Screen capture lightened.


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